1. Field of the Invention
This invention relates to archery arrow systems and more particularly to hunting and target arrows for use with various long bows, recurve bows, compound bows, crossbows, and other bows, or means for casting arrows, spears, or bolts, and other projectiles capable of carrying arrowheads.
2. Description of the Related Art
It is known that the ability of an arrow to be cast accurately is of the utmost importance. Furthermore, it is well appreciated that a hunting arrow must carry an arrowhead capable of cutting and penetrating the intended game for a quick, clean and humane kill.
In the past, bowhunters have become accustomed to compromising the speed and accuracy of hunting arrows, when compared to that which can be achieved with target arrows. Over the years, separate sets of standards have seemed to evolve for target and bowhunting equipment. Target archery equipment has been designed with the intent of enabling archers to consistently cast swift arrows at distant targets accurately. This equipment has improved to the point where many a target archer can place an arrow through an apple at fifty yards. In fact, quite a few can maintain this level of proficiency repeatedly without missing. Although bowhunting equipment has improved greatly, it has never quite been expected to perform on the level of target equipment. The development of bowhunting equipment has often been the result of compromise in an attempt to solve the more difficult problems.
Well over ninety percent of the individuals who become involved with archery, do so with the intent of hunting. They are intrigued with the challenge of the sport, and purchase equipment which they feel will serve them well. But few archers experience the proficiency that can be attained with target arrows as far as speed and accuracy are concerned. It is quite difficult for most archers to believe that they might pursue game with bowhunting projectiles that may afford them the same level of ability to shoot swiftly, accurately and consistently as in target shooting.
Almost all hunting arrowheads have utilized fixed cutting blades which project outwardly from the main body of the arrow shaft. Hence the term "broadhead" has evolved. These fixed extending blades have been necessary in the past to create an acceptable width of cut upon impact.
Minimizing the weight and aerodynamic instability of these winged arrowheads has been a critical problem. Extra weight on the forward end of any arrow is necessary to create proper balance. It serves as a guiding mass to direct the shaft that follows on a straight course toward the target. Air passing over the extended blades on a broadhead forces it to plane off course. This ill effect on flight is termed windplaning. Extra weight helps to stabilize broadheads in flight, which is one of the major reasons why they weigh more than target arrowheads for the same weight bow. Relatively heavy arrow shafts with stiffer spines are necessary to properly cast the excess weight of broadheads. Extremely large fletching must also be used to create additional drag at the rear of the arrow in order to reduce windplaning enough to maintain adequate flight characteristics.
Any arrowhead with exposed blades presents a safety hazard to the archer while handling. In many cases it is necessary to increase the length of the arrow shaft in order to avoid blade contact with the archers hand, bow handle or riser. This combination of weighty broadhead, heavy arrow shaft and large fletching has become the conventional hunting arrow.
The increased weight and drag of the conventional broadhead tipped hunting arrow causes a considerable reduction in speed. Even the slightest loss of speed will cause a bowhunter's accuracy to diminish substantially, since it is unpredictable how game will move after the shot is released. A target archer need only worry about point to point accuracy since his target is stationary. Bowhunters must also be concerned with the ability of the game to move from the path of the intended shot. Judging distance also becomes more crucial for the archer who is attempting to place the shot of a slower flying arrow, as its elevation drops off more readily with reach.
Through the years, manufactures have greatly increased the efficiency of bows to cast arrows faster. Almost all of the emphasis has gone into developing the mechanisms for casting arrow projectiles, with only minimal attention being given to the development of the projectiles themselves. Manufactures have been quite concerned about the speed of arrows coming out of the bows they produce. Arrow Velocity in feet per second, out of the bow, has become one of the dominant marketing issues.
In reality, the most important issue as far as arrow speed and bowhunting accuracy is concerned, is not how fast an arrow comes out of a bow, but how long it takes to reach the target. All of the factors which govern the speed of an arrow after it leaves the bow must be considered in order to develop a projectile that will be the swiftest to the target. It is true that faster arrows have a flatter trajectory, but trajectory is only part of the total concern for accuracy in hitting the point of aim on a target that may move. Speed to the target certainly becomes easier to appreciate when you consider that game is almost always moving to some extent. The kill area on a deer, for example, is about the size of a paper plate. If this game were to take just half a step in the time it takes the arrow to make contact, it is most probable that a wounding hit or complete miss would result, instead of the quick kill that may have harvested the game had it been stationary.
In recent years, manufactures have begun to promote bows capable of increased arrow velocity by enabling archers to shoot shorter arrows. These bows, termed "overdraws", incorporate an extension arrow rest that will support the front of an arrow drawn behind the normal drawing point. Although they will cast shorter, lighter and therefore faster arrows, their use involves some degree of compromise to the archers ease in shooting accurately. Overdraw bows are considered less forgiving to shoot, as even minimal torquing or tilting of the bow upon release can cause the arrow to be cast off course. Safety must also be considered in the use of these bows, as the head of the arrow may be drawn behind the archers bow hand.
Careful comparison of hunting and target projectiles reveals some important differences. A complete standard length hunting arrow including, shaft, nock, fletching, glue, insert and arrowhead, weighs from thirty nine to forty one percent more than a complete target arrow for the same draw length and weight of bow, depending on shooting styles. Hunting arrows, again depending on shooting styles, will take from twenty-five to twenty-nine percent longer than target arrows, to reach a target at twenty yards.
Foreshortened hunting arrows that may be used on overdraws weigh more than standard weight target arrows for the same weight full draw bow. Therefore hunting arrows still end up weighing more than target arrows even if a bowhunting archer is willing to compromise shooting ease in an attempt to reduce weight for faster flight.
Even when you compare a broadhead tipped hunting arrow to a target arrow having the same weight, the target arrow will have a considerably flatter as well as faster trajectory. This is due to the fact that the necessary extra forward weight in any arrow will cause it to travel in flight with its forward tip downward. Gravity will cause any arrow to loose altitude on the way to a given target. In the case of broadhead tipped shafts during flight, the downward orientation of the blade surfaces forces the head to plane downward, further increasing the arrow's descent. As mentioned before, the blades and necessary large fletching on a broadhead tipped hunting arrow will create excessive speed reducing drag that is not present on target arrows.
If we value our wildlife resources, and appreciate the game we pursue, it is imperative that we seek to devise and utilize equipment that will afford bowhunters the same degree of shooting proficiency as achieved by target archers.
Accordingly, there has been a continued need for a hunting arrowhead that would have at least the same ability to be cast with the speed and accuracy as a target arrowhead. Furthermore, such an arrowhead must be capable of efficiently creating a wide external cut and deeply penetrating so as to effect a quick kill, and produce a blood trail essential for tracking and properly harvesting game. This may be best accomplished by using a hunting arrowhead having the same weight and flight characteristics as a target arrowhead so that it might actually be cast on a standard target arrow shaft.
The prior art is objectionable in this regard, as it has traditionally suggested configurations that have required extra weight for sufficient penetration, and as mentioned before, for broadhead stability in flight. There is need for such a hunting arrowhead, having improved penetration performance so as to not require any additional weight beyond that which is used in standard target arrowheads on target arrows. Furthermore, past hunting arrowhead designs have been primarily configured to wedge their way, which thereby creates a restricted path having considerable friction. This inefficient use of the stored kinetic energy in a decelerating arrow, results in the overall reduction of shock, penetration, hemorrhaging, and bleed-out, that may be achieved.
The prior art is also objectionable as target and hunting arrowhead designs have had the inherent problem of transmitting shock to the shaft on which they are mounted during acceleration. The mass of these past arrowhead configurations will transmit excessive inertial shock during acceleration, causing the arrow shaft to bend, which reduces the accuracy of the arrow when cast. Higher spined, heavier and therefore slower flying arrow shafts have been necessary in order to properly cast these arrowheads.
Accordingly, there is a need for hunting and target arrowheads which are capable of reducing the shock of the inertial forces they transmit to the arrow shaft during acceleration.
Few attempts have been made to devise a slender hunting arrowhead having no diametric extensions, but rather having completely enclosed moveable blades that are intended to open upon immediate impact, prior to penetration, and thereby eliminate the problems of windplaning. Examples of such devices are suggested in U.S. Pat. Nos. 2,859,950 of Doonan and 4,579,348 of Jones. A major problem associated with these designs is the inability of their blades to efficiently, as well as effectively, open to create a wide exterior cut upon impact with the game.
In the case of the Doonan device, there is presented a blade camming mechanism which is intended to induce pivotally carried blades from a rearward completely enclosed position, to an extended open outward cutting position. In the open cutting position, the blades are not permitted to swing forward for easy removal from the game, which therefore makes it illegal for use in some states that do not permit the use of barbed arrowheads. The configuration of this mechanism in relation to its leveraging of the blades open while cutting permits all of the forces exerted against the blades to urge them to retract thereby making it difficult for them to remain open to cut a wide path. This mechanism is further lacking in camming leverage to sufficiently angle its blades open to a wide cutting diameter. It also requires the use of an exceptionally large amount of the kinetic energy stored in a decelerating arrow in order to open its blades on impact. Furthermore, it is questionable as to whether or not this mechanism will actually open its blades wide to produce a large exterior wound. This is dependant upon the degree of obstruction the head encounters when striking the game.
In respect to hunting arrowheads that employ parts intended to move rearward with reference to the arrow shaft and thereby open blades to an outward cutting position, all the parts capable of relative movement with the shaft must be recognized as separate projectiles. The head, blades and pin in the Doonan mechanism represent a substantial mass portion of the entire arrow projectile. This mass portion has its own kinetic energy stored in it during flight, and is therefore capable of considerable penetration on its own before it will slow enough for the shaft behind to force into it and press the blades outward. It is also important to note that the frictional resistance which was used to hold the blades closed during acceleration and flight must also be overcome before the blades can open. While it is probable that this mechanism will open and create an exterior cut in the hide when striking a rib for example, it is less probable it will open on impact with just the hide and softer matter between the ribs.
There is, therefore, a need for an improved hunting arrowhead which can efficiently open its blades from an enclosed position to a wide cutting position on impact, prior to penetration, so as to insure a wide exterior cut without regard to where it strikes the game, as well as not permitting all of the forces exerted against the blades while cutting to urge them to retract.
The Jones mechanism utilizes fully enclosed blades in a forward orientation relative to the arrow shaft. A problem with this mechanism is that it incorporates a plunger designed to open its blades by pressing against the sharpened edges, which results in dulling. Again, there is objection to the minimal blade opening this plunger will provide on impact, prior to penetration, as well as the inefficiency of its blades having to overcome the biasing pressure of the clutch which holds the blades closed during acceleration and flight.
The inability of prior art large blade hunting arrowheads to efficiently produce the greatest amount of cutting also presents a problem. Friction against large blade surfaces creates unnecessary drag that quickly uses up stored kinetic energy. There is a long felt need for a hunting arrowhead having minimal size blades and an effective configuration which will employ them to efficiently cut a wide maximum path with extended depth penetration.
The Doonan mechanism derives its blade opening force from the pressure against the arrowhead as it penetrates. As mentioned before, it lacks sufficient camming leverage to open its blades to a wide cutting diameter. It is also important to point out that it provides only minimal mechanical leverage to hold its blades open as it penetrates. It is objectionable that the Doonan mechanism may not have the ability to open its blades on impact, before penetration. It is even more objectionable when the ability to create a wide exterior cut becomes less certain as the blades may lack sufficient leverage to stay open when expected to cut.
The blades in the Doonan mechanism may be forced to retract when they encounter denser unyielding materials such as tough hide or bone, and have the potential to reopen upon entering more penetrable matter. However it is objectionable that this mechanism has no certain minimal cutting diameter. It is also objectionable that if the head itself were to strike bone, the blades cannot readily retract. In this case increased leveraging force will unnecessarily urge the blades to cut wide as the body wedges through thereby inefficiently using the stored kinetic energy in a decelerating arrow which may have been saved for further cutting and penetration.
Accordingly, there is need for an improved hunting arrowhead which is capable of efficiently creating a wide exterior cut on entry, having retractility of blades to a minimum cutting width to enable more effective penetration on bone, and being further capable of wide cutting after passing through the bone while maintaining the ability to be easily withdrawn.
Examples of exposed blade hunting arrowhead mechanisms which are intended to open wider on or after impact are presented in U.S. Pat. Nos. 4,099,720 of Zeren and 4,452,460 of Adams. These present the same aerodynamic instability problems as exposed fixed blade hunting arrowheads during flight and are likewise objectionable as they cannot eliminate windplaning.
Other prior art hunting arrowhead developments that have been directed toward mechanisms having completely enclosed or almost completely enclosed blades are presented in U.S. Pat. Nos. 3,738,657 of Cox and 4,166,619 of Bergmann et al. These mechanisms are intended to open after penetrating through the exterior of the target. They are objectionable due to their inability to produce a wide exterior cut which is necessary for sufficient bleed-out to create a trail essential for tracking in order to properly harvest the game.